Abstract

Understanding the landscape distribution of invasive species has become an important tool to help land managers focus their efforts. We used land cover data to predict the proportion of wetlands in a watershed dominated by reed canarygrass (Phalaris arundinacea L.), one of the most dominant wetland invaders in North America over the past century. Our results indicated that the landscape configuration of a watershed was a better predictor than the landscape composition of a watershed, with the adjacency of wetlands to agriculture and open water identified as the best predictors of the proportion of wetlands in a watershed dominated by reed canarygrass. In contrast, proportion of agriculture and open water were identified as the next best predictors in our regression tree, but explained significantly less variability. These results suggest that the risk of invasion by reed canarygrass varies among watersheds, and further that the potential for restoration success may similarly vary across the landscape. We argue that it is essential to understand the landscape context of a wetland before attempting a restoration project because success may be mediated by factors outside the local site.

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Acknowledgments

Thanks to Monica Turner, whose landscape ecology class inspired this project. Thanks to Tom Bernthal, Kevin Willis, and the Wisconsin DNR for the use of their data. Finally, thanks to several anonymous reviewers whose suggestions greatly improved the manuscript.